Thermal vaporizer

ABSTRACT

A cordless thermal vaporizer of the liquid type wherein the body of the vaporizer has a heater for heating a wick for drawing up a chemical solution from a bottle, and a socket disposed under the heater and removably fittable in the form of a cap to the bottle for attachment thereto. The body is reduced in weight and thereby made attachable to an electric outlet with stability. The solution bottle can be attached directly to the socket of the body and is therefor easy to replace.

TECHNICAL FIELD

The present invention relates to devices for thermal vaporization, andmore particularly to thermal vaporizers of the so-called cordless typefor use as directly attached to electric outlets provided on interiorvertical surfaces as of walls, pillars, etc.

BACKGROUND ART

Thermal vaporizers, such as electric mosquito controlling devices,include those of the mat type wherein a mat impregnated with aninsecticidal solution is used as placed on a heat plate, and those ofthe liquid type wherein a chemical solution is heated for vaporizationwhile being drawn up through a wick from a bottle. Those of the mat typeinclude cordless devices already proposed, while cordless devices of theliquid type have yet to be proposed. The electric mosquito controllingdevice of the liquid type is relatively heavy in its entirety since theoverall weight of the device includes the weight of the device body andthat of the solution bottle. If cordless, the entire device must besupported against gravity solely by a plug attached to the electricoutlet. It is therefore likely that the plug will slip off the outletwhen the device is heavy. This defect has been a serious obstacle toovercome in designing cordless liquid-type devices. For example, theconventional electric mosquito controlling device of the liquid typewith a cord comprises a box-shaped body and is used with a solutionbottle accommodated in the body. The device body of the conventionalstructure must have a height at least sufficient for the body toaccommodate the solution bottle and the wick projecting upward from thebottle, and is consequently large-sized, heavy and unsuited for use as acordless device. The device is further inconvenient in that the bottomportion of the device body needs to be removed when the solution bottleis to be accommodated in the body.

DISCLOSURE OF THE INVENTION

The main object of the present invention is to provide a cordlessthermal vaporizer of the liquid type which is usable as attached to anelectric outlet reliably with stability.

Another object of the invention is to provide a cordless thermalvaporizer of the liquid type wherein a chemical solution bottle can beattached to the body of the device easily.

Still another object of the invention is to provide a thermallyvaporizable chemical solution which is usable for a prolonged period oftime for thermal vaporization and can therefore be used as contained ina small bottle.

Other features of the present invention will become apparent from thefollowing description.

The present invention provides a cordless thermal vaporizer for use witha plug inserted in an electric outlet, the vaporizer being characterizedin that the body of the vaporizer is internally provided with a heaterfor heating a wick for drawing up a chemical solution from a bottle, anda socket disposed under the heater and removably fittable in the form ofa cap to the bottle for attachment thereto.

The thermal vaporizer of the present invention is so constructed thatthe body thereof can be fittingly attached, at its socket in the form ofa cap, to the chemical solution bottle. Accordingly, the body is smallerin size, especially in the dimension along the direction of its height,and in weight than the box-shaped conventional one. The reduced weightlessens the burden on the plug blades inserted in the outlet during use,almost completely eliminating the tendency for the plug to slip off theoutlet and making the vaporizer usable as attached to the outletreliably with stability.

Since the solution bottle can be attached directly to the socket of thevaporizer body, the bottle is easy to fit in and remove.

According to the present invention, the plug is provided on the rearside of the vaporizer body. Electric outlets are divided into two types:the vertical type for use with (two or three) plug blades as arrangedvertically, and the horizontal type for use with plug blades as arrangedhorizontally. Either the vertical type or the horizontal type is used incountries depending on the domestic situation. When the plug isrotatable through an angular range of 0 to 90 degrees relative to therear side of the body to make the arrangement of the plug bladesselectively changeable to the vertical or horizontal direction, thevaporizer is usable for either one of the two types of outlets, henceconvenient.

According to the present invention, the vaporizer body can be providedat its lower end with a skirt for forming a circumferential clearancearound the outer periphery of the solution bottle. The skirt functionsas a protective member for protecting the solution bottle from externalimpact and further as a cover member for holding the bottle out ofsight. Further when the clearance is made to communicate with theinterior of the body, an air current flows upward through the clearanceinto the body, permitting a vapor of chemical to be entrained in theupward air current, whereby the chemical vapor can be diffusedeffectively.

The thermally vaporizable chemical solution to be used as contained inthe solution bottle according to the invention is a solution of at leastone of chemicals such as insecticides, bactericides, repellents,miticides plant growth regulating agents, rodenticides, cosmetics,medicinals, perfumes, deodorants, herbicides, fungicides, insectrepellents for clothes, mold inhibitors, etc. When required, variatousadditives such as synergists and antioxidants are added to the solution.

Preferably, these chemicals have a high vapor pressure of at least3.5×10⁻⁸ mm Hg/20° C. Examples of such chemicals are given below.

Insecticides

(S)-2-Methyl-4-oxo-3-(2-propynyl)cyclopent-2-enyl(1R)-cis·trans-chrysanthemate (common name: Prallethrin, brand name: Etoc,product of Sumitomo Chemical Co., Ltd., hereinafter referred to as "AC")

1-Ethynyl-2-methyl-2-pentenyl cis·transchrysanthemate (hereinafterreferred to as "AO")

1-Ethynyl-2-methyl-2-pentenyl2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropane-1-carboxylate(hereinafter referred to as "AP")

1-Ethynyl-2-methyl-2-pentenyl 2,2,3,3-tetramethylcyclopropanecarboxylate(hereinafter referred to as "AQ")

1-Ethynyl-2-methyl-2-pentenyl2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane-1-carboxylate(hereinafter referred to as "AR")

2-Methyl-4-oxo-3-(2-propynyl)cyclopent-2-enyl-chrysanthemate(hereinafter referred to as "AS")

0,0-Dimethyl 0-(2,2-dichloro)vinyl phosphate (hereinafter referred to as"AT")

o-Isopropoxyphenyl methylcarbamate (hereinafter referred to as "AU")

Deodorants

Lauryl methacrylate, geranyl crotonate, citronella oil and lemon grassoil

Bactericide

p-Chloro-m-xylenol (PCMX) and thiabendazole (TBZ)

Rodent repellents

N,N-Diethyl-m-toluamide (Deet) and dimethyl phthalate

Insect repellents for clothes

Empenthrin, naphthalene and p-dichlorobenzene

Suitable solvents for dissolving the chemical are those having a boilingpoint of up to 350° C. Examples of such solvents are water, Deet,alcohol, silicone, aliphatic hydrocarbons, etc. Especially suitablealiphatic hydrocarbons are those having a boiling point of 150° to 350°C.

The concentration of the chemical solution is about 1 to about 80 wt. %,preferably about 6 to about 75 wt. %, more preferably about 15 to about50 wt. %.

It is desirable to prepare the chemical solution from a chemical havinga high vapor pressure and a solvent having a boiling point of up to 350°C. (a boiling point of 150° to 350° C. in the case of aliphatichydrocarbons). The chemical solution is then usable in a small amount ofabout 7.5 ml for thermal vaporization for a long period of time of atleast 720 hours. Accordingly, the solution bottle to be used can besmall, with the result that the thermal vaporizer can be attached to theoutlet more reliably with higher stability.

The wick to be provided on the solution bottle may be made of any ofvarious materials commonly used, such as felt, cotton, pulp, nonwovenfabric, asbestos, inorganic molding, etc. Preferred wicks are those madeof felt, biscuit, pulp and inorganic molding. Examples of moldedinorganic wicks are those prepared from porcelain porous material, glassfiber, asbestos or like inorganic fiber in the form of solid pieces withuse of a binder such as gypsum, bentonite or the like, or those preparedfrom a mineral powder such as kaolin, activated clay, talc, kieselguhr,clay, perlite, bentonite, alumina, silica, alumina silica, titanium,fired vitreous voltanic rock powder, fired vitreous volcanic ash powderor the like, as used singly or in combination with wood flour, carbonpowder, activated carbon or the like, in the form of solid pieces, usinga glue such as dextrin, starch, gum arabic, synthetic glue,carboxymethyl cellulose or the like. More preferably, the wick isprepared from 100 parts by weight of such a mineral powder and 10 to 300parts by weight of wood flour or a mixture of wood flour and carbonpowder and/or activated carbon in an amount equal to that of wood flourin weight, by admixing with the resulting mixture 5 to 25 wt. % of aglue based on the wick to be obtained, kneading the mixture withaddition of water, extruding the mixture and drying the extrudate. It isdesired that the wick be 1 to 40 hours, more desirably 8 to 21 hours, inoil absorption speed. The term "oil absorption speed" means a valuedetermined by immersing the wick, as dimensioned to 7 mm in diameter and70 mm in length, in liquid n-paraffin at 25° C. over a length of 15 mmfrom its lower end and measuring the time required for the n-paraffin toreach the top of the wick. The wick may have incorporated thereinpigments such as Malachite Green, fungicides such as sorbic acid, saltsthereof and dehydroacetic acid, etc. in addition to the mineral powder,wood flour and glue.

The heater to be used in the vaporizer is generally an electric heaterwhich produces heat when energized, whereas the heater is not limited tothe electric one but can be any known heater including, for example, amaterial which produces heat on oxidation in air or a pyrogenic materialutilizing platinum catalyst or the like.

BEST MODE OF CARRYING OUT THE INVENTION

Various embodiments of the invention will be described below withreference to the accompanying drawings.

FIG. 1 is a view in vertical section showing a first embodiment of theinvention;

FIG. 2 is a view in vertical section showing the first embodiment with achemical solution bottle attached thereto;

FIG. 3 is a bottom view showing a modification of the first embodiment;

FIG. 4 is a perspective view showing a second embodiment of theinvention;

FIG. 5 is a view in vertical section of the same;

FIG. 6 is a view illustrating an example of means for limiting therotation of a rotatable member of the same;

FIG. 7 is a side elevation showing a third embodiment of the invention;

FIG. 8 is a bottom view of the same;

FIG. 9 is a rear view of the same;

FIG. 10 is a view in section taken along the line A--A in FIG. 8 andshowing the same in use;

FIG. 11 is a view in section taken along the line B--B in FIG. 8 andshowing the same with a heater omitted; and

FIG. 12 is a view in vertical section showing a preferred example ofchemical solution bottle in use.

FIG. 1 shows a first embodiment of the invention designed specificallyfor use with an outlet with blades in a horizontal arrangement. Theembodiment has a vaporizer body 1 comprising a flat bottom portion 2 anda semispherical cover portion 3. A vapor outlet 4 is formed in thecenter of the top of the cover portion 3. A ring heater 5 having anopening extending vertically therethrough is provided inside the body 1below the vapor outlet 4. The heater 5 is supported at an outer flange5a thereof by a stay 6 on the bottom portion 2. Provided under theheater 5 is a bottle socket 7 projecting upward from the bottom portion2 and having an opening extending vertically therethrough. The socket 7is formed on its inner periphery with a threaded portion 10 adapted forscrew-thread engagement with a threaded portion 9 on the outer peripheryof the mouth 8a of a chemical solution bottle 8 (see FIG. 2). As seen inFIG. 2, the solution bottle 8 is provided with a wick 11 which isinsertable into the ring heater 5 concentrically therewith when thebottle 8 is attached at its mouth 8a to the socket 7. Plug blades 12(two blades in a pair) in a horizontal arrangement are fixed to thelower end of the body 1 on its rear side. The plug blades 12 areconnected to the respective terminals 13, 13 of the ring heater 5 withlead wires (not shown) in the usual manner. A switch 14 for turning onand off the heater 5 is provided at the lower end of the body 1 on itsfront side. As seen in the bottom view of FIG. 3, air intakes 15 can beformed in the bottom portion 2 of the body. The air intakes 15 serve todiffuse the chemical on vaporization.

When the vaporizer is to be used, the solution bottle 8 is attached atits mouth 8a to the socket 7 on the body bottom portion 2 by thescrew-thread engagement of the threaded portions 9, 10, whereby the wick11 of the bottle 8 is inserted into the ring heater 5 concentricallytherewith. In this state, the heater is energized by inserting the plugblades 12 into an outlet (not shown), whereupon the ring heater 5produces heat to heat the upper portion of the wick 11. A chemicalsolution can therefore be vaporized in the same manner as is the casewith a device having a cord.

The vaporizer is used for insecticidal application by heating the wick11 at a suitable temperature at which the chemical solution in thebottle 8 can be vaporized from the wick 11. The heating temperature isnot limited specifically but is suitably determined, for example,according to the kind of insecticidal or like solution. The surfacetemperature of the heat producing member is usually in the range ofabout 70° to about 150° C., preferably 110° to 145° C. In terms of thesurface temperature of the wick 11, this range corresponds to about 60°to about 135° C., preferably about 95° to about 130° C.

Since the solution bottle 8 can be attached at its mouth 8a to thesocket 7 on the body bottom portion 2, the bottle 8 is very easy toattach to and remove from the body 1. Because the socket 7 of the body 1is merely fitted in the form of a cap to the mouth 8a of the solutionbottle 8, the body 1 is diminished in size, especially in the dimensionin the direction along its height. This results in a correspondingdecrease in the weight of the body 1, i.e., of the entire vaporizer,rendering the vaporizer attachable to the outlet with stability. Thesolution bottle 8, which is left exposed, can be prevented from beingoverheated by the heater and has the advantage that the amount ofremaining solution can be readily checked through the bottle.

Although the screw-thread engagement between the threaded portions 9, 10is resorted to for attaching the solution bottle 8 to the socket 7, thethreaded portions 9, 10 may alternatively be replaced by a projectionand an indentation which are engageable with each other. The solutionbottle 8 may be sized as desired insofar as the vaporizer can beattached to the outlet free of trouble.

When the thermal vaporizer of the present invention is to be used asattached to a double outlet, it is likely that the body 1 (including thebottle 8) attached to one of the outlets will cover the other outlet tomake the other outlet unusable depending on the size of the body 1.Accordingly, it is desired that the dimensions of the vaporizer aboveand below the plug blades 12 be smaller than the spacing between theupper and lower outlets. For example, when the distance between theadjacent inner ends of the two outlets is 25 mm, the distances D1 and D2shown in FIG. 2 are made not greater than 25 mm.

FIGS. 4 to 6 show a second embodiment of the invention which issubstantially the same as the embodiment of FIGS. 1 and 2 except that itis usable for both the outlet with plug holes in horizontal arrangementand the outlet with plug holes in vertical arrangement.

With this embodiment, a rotatable member 16 having a pair of plug pieces12, 12 opposed to each other with the center of rotation positionedtherebetween is fitted in the rear side of the body 1 centrally thereof.The rotatable member 16 has at its base end a disc portion 16a formedwith an annular groove 17 in its outer periphery. An annular ridge 18 onthe body 1 is fitted in the groove to render the rotatable member 16rotatable. The plug pieces 12 may be pins or blades, or three pinsincluding a grounding pin are usable as desired.

With reference to FIG. 6, the annular ridge 18 on the body 1 has acutout 19 over an angular range of 90 degrees. A protrusion 20projecting from the bottom of the annular groove 17 in the rotatablemember 16 is fitted in the cutout 19. As indicated by arrows in FIG. 6,the protrusion 20 is movable with the rotation of the rotatable member16 through the cutout 19 over the angular range of from 0 to 90 degrees.For example when the protrusion 20 bears on one end of the cutoutportion 19 as shown in FIG. 6, the pug pieces 12, 12 are arrangedvertically, whereas when the protrusion bears on the other end of thecutout portion, the plug pieces are arranged horizontally.

According to the present embodiment, the plug pieces 12, 12 can bepositioned selectively in the horizontal or vertical arrangement asdesired by rotating the rotatable member 16. In foreign countries,outlets are available in two types, i.e., horizontal and vertical, withrespect to the arrangement of plug holes. The device with the plugusable for the two types is suited especially for export.

The rotatable member 16 has a seat portion 16b projecting outward fromthe central part of the disk portion 16a. The seat portion 16b has theplug pieces 12, 12 fixedly implanted therein. When the plug pieces 12,12 are inserted into the outlet (not shown), the seat portion 16bprovides a space between the body 1 and the outlet, consequently betweenthe body and a pillar or wall, preventing the vapor of chemicalcomponent from depositing on the pillar or wall when the vapor isreleased from the top outlet 4 of the body 1. The seat portion 16b maybe dispensed with.

FIGS. 7 to 11 show a third embodiment of the invention which issubstantially the same as the embodiment shown in FIGS. 1 and 2 exceptthat a skirt 21 is formed integrally with the lower end of the body 1.

As will be apparent from the sectional view of FIG. 10 showing theembodiment in use, the solution bottle 8 attached to the socket 7 on thebody 1 is surrounded by the skirt 21, which serves as a cover member forholding the solution bottle 8 out of sight and as a protective memberfor protecting the bottle 8 from impact or damage to be applied orcaused thereto from outside. These two functions give an attractiveappearance to the product and make it usable with safety.

A circumferential clearance 22 formed between the solution bottle 8 andthe skirt 21 is in communication with the interior of the body 1 throughthe intakes 15 in the bottom portion of the body 1, permitting outsideair to flow into the body 1 smoothly. The upward current produced insidethe body 1 diffuses the chemical with improved effectiveness onvaporization. Such an improvement in the diffusibility of the vaporizedchemical can be achieved favorably especially by giving the vapor outlet4 an overall opening area which is 2 to 40 times, preferably 5 to 15times, the cross sectional area (thickness) of the wick 11 and makingthe total opening area of the air intakes 15 1.5 to 20 times, preferably3 to 10 times, as large as the wick cross sectional area. The intake ofoutside air into the body 1 prevents the overheating of the bottle 8 andthe rise of internal pressure thereof, thus serving to prevent leakagefrom the solution bottle 8. The intake 15 may be formed in a sideportion of the body 1.

According to the present embodiment, the skirt 21 can be formed at theupper end of its rear side with a projection 23 projecting outward so asto be flush with the rear face of the plug block 12a at the block lowerend. When the plug is attached to the outlet, the projection 23 bearsagainst the outlet face under the lower end of the plug block 12a tosupport the product against gravity by bearing contact with the outlet.This serves to lessen the gravitational load on the outlet-insertedportions of the plug, permitting the product to be held attached to theoutlet with improved stability.

When the skirt 21 is made suitably detachable from the body 1 at aprojection-indentation fitting portion 24, the solution bottle 8 can beconveniently replaced with the skirt 21 removed. When the skirt 21 isgiven the largest possible inside diameter, solution bottles 8 rangingfrom small to large sizes are usable free of trouble.

When the plug block 12a is rotatable or slidable with the plug pieces 12made retractable into the body 1 suitably, the vaporizer can be packagedor stored in a compacted state, hence convenient.

FIG. 12 shows a preferred example of chemical solution bottle 8 whereina balance hole 25 is formed in its cap. When the internal temperature ofthe bottle 8 rises to raise the internal pressure during use for thermalvaporization, the balance hole 25 releases the pressure to the outside,thus serving to automatically maintain the internal pressure of thebottle 8 in balance with the external pressure. The pressure balancethus ensured completely eliminates the likelihood that the solution willspill out from the bottle 8 through the wick 11. The balance hole 25 maybe preformed, or the bottle cap may have a thin wall portion for formingthe balance hole 25 therein when the vaporizer is to be used. Thebalance hole 25, when preformed, may be closed with a seal before use.

The solution bottle 8, which is left exposed at its lower portion, hasthe advantages that the bottle can be prevented from being overheated bythe heater and permits the user to recognize the amount of remainingchemical solution like those of FIGS. 1 to 6.

According to the invention, the heater 5 may be suspended by a support(not shown) from the cover portion 3 of the body 1 centrally thereof.

The cordless thermal vaporizer of the liquid type embodying theinvention is so constructed that the body 1 thereof is attachable to thesolution bottle with its socket 7 fitted thereto like a cap. The body 1is therefore smaller and more lightweight than box-shaped bodies.Accordingly, the vaporizer can be used as attached to the outletreliably with good stability, with a reduced gravitational load on theoutlet-inserted plug portions. Further because the solution bottle 8 canbe attached to the socket 7 of the body 1 as directly fitted thereto,the bottle 8 is easy to attach to and remove from the body 1.

Thus, the present invention provides a cordless thermal vaporizer of theliquid type which is usable as attached to an outlet with goodstability, along with a chemical solution bottle which is easy toreplace.

Chemical solutions useful for the thermal vaporizer of the inventionwill be described below in greater detail.

Experimental Examples 1-23

Chemical solutions for use in the invention were prepared by mixingtogether specified proportions of the insecticide AC, AO, AP or AQ,organic solvent and, when required, the comound CA, CB or CQ as listedin Table 1.

                  TABLE 1                                                         ______________________________________                                        Example   Insecticide                                                                              Compound   Solvent                                       No.       (wt. %)    (wt. %)    (wt. %)                                       ______________________________________                                         1        AC (16)               BF (84)                                        2        AC (16)               BB (84)                                        3        AC (16)               BC (84)                                        4        AC (16)               BD (84)                                        5        AC (24)    CA (0.3)   BD (75.7)                                      6        AC (24)               BD (76)                                        7        AC (24)    CB (0.3)   BD (75.7)                                      8        AC (24)    CQ (0.3)   BC (75.7)                                      9        AC (24)               BA/BF (38/38)                                 10        AC (24)               BB/BE (38/38)                                 11        AO (16)               BB (84)                                       12        AP (19)               BA (81)                                       13        AP (9)                BB (91)                                       14        AP (18)    CA (0.3)   BC (81.7)                                     15        AP (24)               BD (76)                                       16        AP (24)               BA/BC (38/38)                                 17        AQ (19)               Bb (81)                                       18        AQ (9)                BC (91)                                       19        AQ (37)               BD (63)                                       20        AQ (24)    CA (0.6)   BE (75.4)                                     21        AQ (24)               BA/BD (38/38)                                 22        AQ (24)               BB/BC (38/38)                                 23        AR (16)               BB (84)                                       ______________________________________                                    

The symbols used for the solvents given in Table 1 represent thefollowing.

BA: aliphatic hydrocarbon boiling at 150°-180° C./760 mm Hg.

BB: aliphatic hydrocarbon boiling at 180°-210° C./760 mm Hg.

BC: aliphatic hydrocarbon boiling at 210°-240° C./760 mm Hg.

BD: aliphatic hydrocarbon boiling at 240°-270° C./760 mm Hg.

BE: aliphatic hydrocarbon boiling at 270°-300° C./760 mm Hg.

BF: aliphatic hydrocarbon boiling at 300°-350° C./760 mm Hg.

The insecticides listed in Table 1 have the following vapor pressure.

AC: 3.5×10⁻⁵ mm Hg/20° C.

AP: 1.6×10⁻³ mm Hg/30° C.

AQ: 3.0×10⁻³ mm Hg/30° C.

AR: 5.0×10⁻⁴ mm Hg/30° C.

COMPARATIVE EXAMPLE 1

A comparative chemical solution was prepared using 12 wt. % ofPhthalthrin (product of Sumitomo Chemical Co., Ltd.) having a vaporpressure of 3.5×10⁻⁸ mm Hg/20° C. and serving as an insecticide and 88wt. % of BD serving as a solvent. BD stands for1,3,4,5,6,7-hexahydro-1,3-dioxo-2-isoindolyl methyl-dl-cis·transchrysanthemate.

A 7.5 ml quantity of each of the chemical solutions prepared in Examples1 to 4 and the comparative solution obtained in Comparative Example 1was placed into the bottle 8 shown in FIG. 2. The heater 5 was energizedto heat the upper portion of the wick 11 from therearound to atemperature of 115° C. and thereby test the solution for thevaporization of the insecticide in the solution. The wick 11 wasprepared by admixing 20 parts by weight of starch and water with 60parts by weight of perlite and 20 parts by weight of wood flour,kneading the mixture and extruding the mixture, followed by drying (6 mmin diameter and 70 mm in length, about 14 hours in oil absorptionspeed). The heater 5 used was in the form of a disk having an insidediameter of 10 mm and a thickness of 10 mm.

The amount of vaporized insecticide was determined by trapping the vaporin a silica gel column by aspiration every hour, subjecting the silicagel to extraction with chloroform and quantitatively analyzing theextract by gas chromatography after concentration.

Table 2 shows the results obtained by determining the amount ofvaporization of the insecticide (mg) per hour, 10 hours, 100 hours, 200hours, 300 hours and 720 hours after the start of heating of the sample.

                  TABLE 2                                                         ______________________________________                                                 Hours after start of heating                                         Sample No. 10       100    200    300  720                                    ______________________________________                                        Example 1  0.80     0.91   0.95   0.91 0.77                                   Example 2  0.93     1.07   1.01   0.88 0.73                                   Example 3  0.91     1.05   0.96   0.94 0.76                                   Example 4  0.88     1.02   1.03   0.97 0.85                                   Comp. Ex. 1                                                                              0.53     0.31   0.22   0.10 0                                      ______________________________________                                    

Table 2 reveals that the use of the chemical solution of the inventionmakes it possible to vaporize the insecticide at a remarkably improvedrate and that the improved rate can be sustained even 720 hours afterthe start of heating almost without a substantial reduction.

The chemical solution of the invention for use with the thermalvaporizer permits the use of a solution bottle of greatly reduced size,while the cordless device can be attached to the outlet reliably withgood stability. Further the chemical solution itself is usable for atleast 720 hours without clogging the wick, consequently assuring thermalvaporization for a prolonged period of time.

We claim:
 1. A thermal vaporizer with an integral plug for insertioninto an electrical outlet, comprising:a vaporizer body; a ring heatermounted within said vaporizer body; a wick having a cross sectionalarea, for drawing up a chemical solution from a bottle which wick isinsertable into the ring heater concentrically therewith; a socketdisposed under said heater with spacing therebetween; a bottle fittablein the form of a removable cap to said socket such that when the bottleis in place, one or more openings are provided for said wick; at leastone air outlet formed in the top portion of said vaporizer body, saidair outlets having a total opening area that is 2 to 40 times the crosssectional area of said wick; at least one air intake formed in thebottom portion of the body and having a total opening area that is 1.5to 20 times the cross sectional area of said wick; and a plugelectrically connected to said ring heater.
 2. A thermal vaporizer asdefined in claim 1 wherein the bottle can be attached to the socket ofthe vaporizer body by screw-thread engagement between an internallythreaded portion of the socket and an externally threaded portion of themouth of the bottle.
 3. A thermal vaporizer as defined in claim 1wherein the plug is provided on the rear side of the vaporizer body soas to be rotatable over an angular range of 0 to 90 degrees to renderthe vaporizer usable for electric outlets of both the horizontalarrangement type and the vertical arrangement type.
 4. A thermalvaporizer as defined in claim 1 wherein the vaporizer body is providedat its lower end with a skirt for forming a circumferential clearancearound the outer periphery of the bottle to be attached to the socket ofthe body, and the clearance is in communication with the interior of thebody.
 5. A thermal vaporizer as defined in claim 1, wherein one of saidintake openings is located in a bottom portion of a main housing of saidvaporizer body, anda second air intake is formed in the socket portion.